Light metals such as magnesium, aluminum, zinc and alloys thereof have properties such as low density, high specific strength and easy processing which are needed in various applications such as aircrafts, electronic devices like portable devices, autos, etc. However, light metals such as magnesium alloys also have low surface hardness and low corrosion resistance and can not effectively meet requirements of these applications.
Micro-arc oxidation (MAO) is a surface treatment technique developed based on anodization technique. Through MAO treatment, a ceramic layer can grow in situ on the surface of a light metal substrate, and this ceramic layer has better hardness and better corrosion resistance.
Sol-gel coating is also a surface treatment which can impart new surface properties to a substrate, and practically, the sol-gel coating can be used to seal an anodization film so as to produce a layer with better chemical stability. Different sol-gel coating compositions and/or coating processes can produce layers with different properties and hence impart different surface properties to the light metal so as to effectively meet requirements in various applications.